Cushion underframe



June 21, 1966 G. w. COPE CUSHION UNDERFRAME 2v sheets-sheet 1 Filed Oct. 25, 1964 June 2l, 1966 Filed Oct. 23, 1964 2 Sheets-Sheet 2 /I 'I' Il lg/m N "S /s g &2

l g f g N t?! i FN',-

l n i i; s "w M 1f i l A//l [im i A I I u, e il 2 I *i l/1| lis ,I l f Q al-- I N// /S'-|| /N la E Q Se e 2 N e R*\ l *,J vv

m e: NI/ENTO? H/S ATTOHNE Y United States Patent O 3,257,000 CUSHION UNDERFRAME Geoffrey W. Cope, Williamsville, N.Y., assignor to Symington Wayne Corporation, Salisbury, Md., a corporation of Maryland Filed Oct. 23, 1964, Ser. No. 405,940 9 Claims. (Cl. 213-43) This invention relates to cushion under'frames for railway cars which employ hydraulic cushioning units for force absorption.

In a conventional cushion underframe in which a lioating sill sliding in a fixed center sill, extends the length of the car, the fica-ting sill is yieldably resisted in its relative longitu-dinal movement by long travel coil springs which absorb practically no force, making the underframe deipendent for force absorption upon the friction engendered between the Ifioating and fixed sills. Within the limits of 'its travel, the fioating sill of a conventional cushion underframe protects its car from damage mainly by transmitting applied longitudinal forces through the floating sill and eliminating the car body as a reactant. It is customary in such unde-rframes to protect the fioating sill itself from damage by interposing draft gears yor like resilient cushioning units 'between it and the couplers. However, since the floating sill in which the units are mounted is `free to move at all times, within the limits of travel of the fioating sill and particularly up to the relatively low limit of travel of a coupler in a fixed underframe car, the force 'absorption by these units is not comparable with that of the same units in a fixed underframe installation. Consequently, while a car equipped with a cushion under-frame is protected, if in the particular train or string it is sandwiched between fixed underframe cars, substantially the full impact of an applied force will be transmitted between the adjoining cars through the floating sill and the stresses on the floating sill will be correspondingly high.

In the :past few years, the force absorptive capacity of cushion underframes has been markedly increased by adding hydraulic cushioning units, so that a substantial part of the kinetic energy of the moving fioating -sill is converted int-o heat by causing its movements to force a viscous liquid through an orifice. The same principle of force absorption has also been embodied in end-of-car cushioning devices for fixed underframe cars which use hydraulic cushioning units lin place of the customary lresilient units.

A hydraulic cushioning unit has a very high force absorptive capacity, but, on low level forces, is not com- 'A parable in effectivenes to a resilient cushioning unit and has a tendency not to operate under low but sustained pressures, such as those encountered during braking and run-ins on grades. An end-of-car cushioning device thus leaves much to'be desired under such conditions. Too, even though the share of an applied ylongitudinal force absorbed by 1a cushion underfram-e is substantially in- -creased by equipping it with a hydraulic unit, the iioating sill is free to move against the resistance of the unit under forces of all levels, with the result that the floating sill can still act as aA rigid force transmitter and if limited in its travel by being sandwiched between fixed underframe cars, will transmit substantially the full impact to the back-up car. Thus, in a coupling operation in which a cushion underfrfame car is backed by one having a fixed underfrarne, the latter will be subjected to a disproportionate share of the applied bufing force, even though the former is equipped with ahydraulic unit.

The primary object of the present invention is to provide a cushion underframe in which longitudinal forces are absorbed by both hydraulic and resilient vcushioning means, but the hydraulic means 'are activated` only by forces at and above a predetermined level.

. 3,257,060 Patented June 21, 1966 Another object of the inventi-on is to provide a cushion underframe in Whichforces are transmitted between a sliding sill member and a coupler through resilient cushioning means and the sill member is blocked from sliding, against the resistance of hydraulic cushioning means, except when the transmitted forces are at and above a predetermined level.

A further object of the invention is to provide a cushion underframe in which longitudinal fiorces are partly absorbed by tforcing a viscous liquid through one or more orifices and 'forcing of the liquid therethrough is prevented, except when the applied force is at or above a predetermined llevel.

An additional object of the invention is to provide a cushion underframe in which hydraulic means either block or permit movement of a sliding sill member in at least one direction, depending upon the level of the applied force.

Other objectsand advantages will appear hereinafter in the detailed description, be particularly ypointed out in the appended :claims and be illustrated in the accompanying drawings, in which:

FIGURE 1 is a plan View of preferred embodiment of of the cushion undervframe of the present invention with portions broken away and shown in section to more clearly illustrate certain of the details of the construction;

FIGURE 2 is a fragmentary side elevational view showing the lioating sill member and adjoining structure of FIGURE 1;

FIGURE 3 is a vertical sectional view on an enlarged scale, taken along lines 3--3 of FIGURE l;

FIGURE 4 is a vertical sectional view on the scale of FIGURE 3 taken along lines 4-4 of FIGURE 2;

FIGURE 5 is a fragmentary horizontal sectional view on a further enlarged scale taken along lines 5--5 of FIGURE 3; and

FIGURE 6 is a fragmentary sectional view on the section of FIGURE 5, of an alternate orifice and valving arrangement.

Referring now in detail -to the drawings in which like reference characters designate like parts, the improved railway car cushion -underframe of the present invention depends, in part, on hydraulic cushioning for absorbing longitudinal forces, but differs from prior hydraulic cushion und-erframes in using resilient cushioning means for cushioning iorces below a predetermined level and activating the hydraulic cushioning means only :for forces at and above that level. While sharing the ability of prior The improved hydraulic `cushion underframe is com? prised of a floating or sliding sill member 1 which is mounted for longitudinal sliding in a fixed center sill 2 of a railway car (not shown). Depending upon the application, the fioating sill member 1 may be a oating sill extending the length of a car or one of a pair of relatively short sill members slidably mounted in opposite ends of the fixed sill 2. Mounting one or both couplers 3, according to whether it is a sill or one of a pair of sill members, the floating sill member 1 mounts for each coupler a resilient cushioning unit, device or mechanism, indicated at 4, such as a conventional spring-friction draft gear or rubber cushioning unit. Of la capacity suitable for cushioning longitudinal forces below a predetermined level, each resilient cushioning unit is so mounted and connected to the associated or related coupler andsill' member, that at least longitudinal forces up to that level are transmitted through it between the sill member and the coupler. When it does move or slide longitudinally in and relative to the fixed sill 2, the floating sill member 1 longitudinally compresses, contracts or telescopes a hydraulic cushioning unit, device or mechanism mounted in the fixed center sill 2 and, in correspondingly contracting or reducing a space within theunit filled with oil or other viscous liquid, forces the displaced oil into an adjoining space through one or more orifices or restricted openings 6. As in a hydraulic unit of a -conventional hydraulic cushion underframe, the restricted flow of the displaced oil through the orifice or orifices 6, cushions and dissipates or absorbs the applied longitudinal force by converting the kinetic energy of the part of the unit 5 moving with the sill into heat which is transferred to ambient air through the surrounding metal.

With the heat generated by displacement of the oil varying directly with the applied longitudinal force and the absorptive capacity of the hydraulic unit 5 very high, the improved underframe of this invention will protect a car and its lading from high level forces by the hydraulic unit. However, unlike prior hydraulic cushion underframes, the iioating sill member 1 in this case, except in returning to normal or neutral position, is locked or held against movement or sliding under applied longitudinal forces below a predetermined level, by normally closing the orifice or orifices 6 by valving 7 that will open only under forces at and above that level and, therebelow, will lock the relatively movable parts of the hydraulic unit 5 against movement in a direction to compress or telescope the unit. Consequently, cushioning of applied longitudinal forces below that level devolves entirely upon the lresilient cushioning units 4, with the hydraulic unit 5 then inactivated or inoperative.

In the embodiment illustrated as exemplary of the invention, there is a pair of floating sill members 1, one mounted in each end of the fixed center sill 2. Each sill member 1 mounts one of the couplers 3 and resilient cushioning units 4 and has connected to it a hydraulic cushioning unit 5. Since the structures at opposite ends of the car are duplicates, the illustration and a description of the structure at one end will suffice for an understanding of the invention.

The illustrated floating, sliding or draft sill member 1 projects beyond the adjoining end of the fixed center sill 2 and is mounted therein for relative longitudinal movement or sliding on a support or cross-plate 8 fixed to the bottom of the fixed sill. The coupler 3 in this embodiment is connected for longitudinal movement in unison to a yoke 9 containing the related resilient cushioning unit 4 and suitably may be a pin-connected type E swivel coupler. Longitudinal or bufiing and draft forces, at least up to a predetermined level, well within the capacity of the resilient unit 4 are transmitted through the latter between the coupler 3 and the floating sill member 1 by providing in the sill member fixed front and rear stop lugs 10 longitudinally embracing the resilient unit and any follower block or blocks 11 needed thereby.

In the embodiment, the hydraulic unit 5 for each floating sill member 1 has a housing 12 containing a cylinder 13 extending longitudinally of the fixed sill 2. A piston 14 slides or reciprocates longitudinally or axially in the cylinder 13, with its head 15 in the cylinder and its rod or stem 16 projecting forwardly therefrom. The hydraulic unit 5 is mounted in the fixed sill 2 rearwardly of the floating sill member 1 with the piston 14, or as illustrated, the cylinder 13, stationary and fixed to the center sill and the other relatively movable part, here the piston, movable relative to the fixed sill and connected for longitudinal movement in unison to the floating sill member. The connection between the floating sill 1 and the piston 14 suitably is made by a rigid connecting tube or sleeve 17 receiving in its opposite ends and welded or otherwise secured to studs 18 on or rigid with and projecting toward each other from the confronting or front and rear -pass to the inner side of the piston ring.

ends, respectively, of the piston rod 16 and the floating sill 1. The piston rod 16 slides through an axial opening or aperture 1 9 in the front wall 20 of the housing 12, which is reinforced by a boss 21. Leakage of the oil or other viscous liquid from the cylinder 13 past the rod 16, suitably is prevented by a gasket 22 held in place by a retainer plug 23 and entry of dirt into the opening from the outside is prevented by a flexible boot 24 covering the exposed part of the rod between the sleeve and the boss 21. Within the cylinder 13, the piston rod 16 is screwed into or otherwise secured to the piston head 15.

While the orifices 6 will be located elsewhere, if the space to which the oil from the cylinder 13 is displaced by the relative movement of the cylinder and the piston 14 is outside the cylinder, that space in the illustrated embodiment is the space in the front part of the cylinder. lt, therefore, is particularly suitable to form the one or more orifices or restricted openings 6 as restricted passages extending through the head 15 and opening forwardly to a side or clear of the rod 16, The location of the orifices 6 'in the head 15 has the advantage that by dividing the head axially into two pieces, bolted or otherwise releasably connected to each other in slightly spaced apart relation, and forming the annular groove 25 for the piston ring 26 along the part-line, a radial cavity 27 is provided within the head through which oil passing through the orifices 6 can Thus, the ring 26 can be made of Teflon, nylon, or like material, with the internal pressure exerted by the oil upon it as the piston 14 moves, ensuring its expansion into fluid-tight engagement with the side wall 28 of the cylinder 13.

ln a conventional hydraulic cushion underframe, the orifices 6 would be open at all times, but, as previously pointed out, in the underframe of this invention, they are normally closed by force or pressure-responsive valv- Iing 7 which opens to permit relative telescoping of the piston 14 an-d cylinder 13 only if the applied longitudinal force is above a predetermined level. In the illustrated embodiment, in which the orifices 6 are formed in and extend axially or longitudinally through the piston head 15, the valving 7 has as its valve or valve element, a substantially flat, circular disk or plate 29 centered on and confronting the rear or advance face 30 of the head 1S and of ya diameter to cover the adjoining ends of the orifices 6. While the valve 29 is fiat, seepage of oil past it in its seated or closed position, to the orifices 6 is read- -ily prevented, without precise machining of the confronting faces 31 and 3f) of the valve and the head 15, respectively, by insetting in preferably dovetail `annular grooves 32 in one of the-se faces, radially inwardly and outwardly of the orifices 6, polyurethane or like oil-resistant seals 33. The valve 29 is normally held closed by a spring-urged control rod 34 extending axially or longitudinally through it, the valve head 15, the piston rod 16, the tube 17 and the rear wall 35 of the floating sill member 1 into the longitudinally extending pocket 36 in the sill member in which the yoke 9 is received.

Sealed against leakage, as by O-rings 37 in the head 15 and the rod 16, the control rod 34 is shift'able longitudinally or axially relative to the piston 14, with its relative movement limited at the front by an end cap 38 and at the rear by a stop ring 39 normally seating in a central recess 40 in the rear face 30 of the head. Rearward movement of the control rod 34 normally is prevented by a front spring 41 encircling it between the end cap 38 and the rear wall 35 of the floating sill 1 and,

when held in its normal or closed position by that spring, the control rod holds the valve 29 closed 4by a valve spring 42 on the rod rearwardly of and acting forwardly of the valve. The front spring 41 is stronger than the valve spring 42, so as normally to hold the stop ring 39 in its recess or seat 4i) forwardly of the valve 29. While projecting into the yoke-receiving pocket 36, with its end cap 3S confronting and adapted to be engaged by the rear end of the yoke 9, the control rod 34 norm-ally is spaced rearwardly from the yoke. As Opposed to the floating sill member 1 that can move rearwardly only when the orifices 6 -are open, the yoke 9 will move rearwardly immediately upon the application of a bufling force to the related coupler 3 against the resistance of the resilient cushioning unit 4. Depending on the oper-ating characteristics of the particular resilient unit 4, a given bufling force within its capacity will produce a corresponding or definite rearward travel or movement of the yoke. Predetermining the force level at which the hydraulic unit S will be activated, thus is simply a matter of fixing or setting, for the resilient unit used, the normal or neutral spacing between the control rod 34 and the yoke 9, so that the rod will be engaged and actuated by v the yoke when the applied bufling force is at or above that level Iand not otherwise. When the control rod 34 is actuated or depressed or pushed rearwardly by the yoke 9, it, in turn, unseats the valve 29 by engaging the stop ring 39 with the valves front face 31. Triggered or activated by the opening of its orifices 6, the hydraulic unit then cushions the applied force so long as the floating sill member 1 continues to move rearwardly in response thereto.

Use of the hydraulic unit 5 to resist or cushion draft forces is not contemplated because their maximum is much lower than that of the buffing forces and well within the cushioning capacity of the conventional spring-friction draft gears that are preferred for use as resilient cushioning units 4; In fact, the only draft forces upon which the illustrated embodiment is intended to act are those immediately following buffing forces above the predetermined level, as the piston 14 returns to normal or neutral position, in which case, the hydraulic unit will have a dampening effect upon the particular draft force.

Limited in its rearward movement, as by rear stops or shoulders 43 on the fixed sill 2 and engageable with its rear wall 35, the floating sill member 1 is normally held in forward or neutral position by one or more return springs 44, each conveniently mounted below the center sill 2 on a holt 45 extending longitudinally thereof and through front and rear brackets 46 and 47 fixed to and depending from the floating sill and an intermediate or stop bracket 48 fixed to and depending from the support plate 8 between the floating sill brackets. With the return springs 44 acting forwardly on the floating sill member 1 -between the latters front bracket spring seat 46 and the stop bracket 4S on the support plate and the stop bracket engageable rearwardly by the rear bracket 47 to limit the forward movement of the sill member, the return springs must be of sufficient strength to move or shift the sill member and the piston 14 forwardly against the resistance of the oil in the cylinder 13. While the oil displaced by forward movement of the piston 14 in the cylinder 13 will exert a dampening action as it passes rearwardly through the orifices 6, the valve 29 will not obstruct such movement since it will be unseated by the rearward pressure of the oil upon it, if, as intended, the opposing force of the control rods front spring 41 is much less than lthe return force exerted by the return springs.

For the illustrated hydraulic unit 5 to perform properly, the cylinder 13 must always be filled with oil and the latter must have room both to expand as it is heated in absorbing the kinetic energy of a bufling force above the predetermined level and to compensate Ifor its displacement by the piston rod 16. To this end lthere is provided in the housing 12 outside and preferably above the cylinder 13, a reservoir 49 fillable through a fill pipe 50 and connectable to the cylinder by access ports 51 suitably valved by check valves (not shown) to permit the oil as it expands under heat to flow from the cylinder into the reservoir, with the reverse flow of the oil practically unhindered so as to keep the cylinder constantly filled.

As opposed to the disclosed embodiment in which the housing 12 of each hydraulic unit 5, containing its cylinder 13, is fixed or anchored to the center sill 2, an instal- .lation in which the floating sill member 1 is a s ill extending the length of the car, ordinarily would require both the cylinder and the piston to be movable relative to the fixed sill so that the hydraulic unit could be compressed by movement of the floating sill in either direction in response to rhurling forces above the predetermined level on the couplers 3. A mounting of the hydraulic unit 5 suitable for enabling the one unit to cushion bufling forces from either end of the car may be a conventional mounting, such as that shown in Settles et al. Patent 3,028,019, issued Apr. 3, 1962, in which the unit is supported in the fixed sill 2 between stops (not shown) fixed thereto and compressed on movement of the floating sill 1 in either direction by stops (not shown) fixed to the floating sill and in neutral position engaging `the ends of the unit. Y

Since in such an installation the piston 14 would not be rigidly connected to the floating sill 1, the valving 7 of the illustrated embodiment would not be suitable. However, the same purpose is served by the alternate arrangement shown in FIGURE 6 in which the pist-on head 1S is provided with -t'wo sets of orifices, one 6a closed at the rear of the head by rear check valves 52 and the other 6b at the front of the head by front cheek valves 5-3. Suitably in the form of spring-loaded balls 54, with the loading springs 55 of berryllium-copper or like practically unbreakable material, the check valves 52 and 53 will resist movement of the piston 14 in either direction. However, by judicious selection' of the springs 55, the front check Val-ves 5=3 can be made to open readily under the return force exerted by the return springs 44, while the rear check valves 52 will open only under the much higher pressure that will be exerted upon them when the bufling force on the floating sill 1 is above the predetermined level, which, in the -main embodiment, would cause the yoke -9 to open the valve 29 by depressing the control rod 34. iBypassing of the valves 52 and 53 through the central cavity 27 on movement of the piston 14 in either -direction is prevented by ysuitably sealing the return orifice 6b from the cavity, as by the illustrated plug 56.

The predetermined force level below which the hydrauli-c unit 5 will vbe locked against operation and above which it will cushion bufling forces, may vary over a considerable range, but, in any case, should be such that the .resilient `cushioning units 4 can readily protect the car and its lading, as well as the sill member 1, against damage from the forces which it must cushion alone. A satisfactory force level thus could well be that developed in a lcoupling operation by impacts at a relative speed of 5 mph., a level well within the cushioning capacity of conventional resilient cushioning units.

Pro-m the above detailed description, it will be apparent that there has been provided an improved hydraulic cushion underframe which possesses the capability of prior cushion underframes of protecting a oar and lading from high level bufllng forces and Imakes use of resilient cushioning units for cushioning lower level forces well within their capacity. vIt should be understood that the describedand disclosed embodiment 'and-alternate valving arrangement are merely exemplary of the invention and that all modifications are intended to be included that do not depart from the spi-rit of the invention and the scope of the .appended claims. v

Having described my invention, I claim:

-1. In a railway car having a fixed center sill, a cushion underframe comprising =a -sill member longitudinally movable in said fixed sill, hydraulic cushioning means in said fixed sill and having a `cylinder filled 'with ya viscous liquid and a piston slidable in `said cylinder, said cylinder and piston being connected to said fixed `sill and sill member for relative sliding thereof on longitudinal movement of said member in response to longitudinal forces thereon, orifice means in a head of ysaid piston for restricted flow of said liquid therethrough on sliding thereof relative to 'said cylinder, valve means Iblocking flow of said fluid in one direction through said orifice means and therethrough said movement of said mem-ber under longitudinal forces thereon below said level, said valve means opening under forces on said member at and above said level for enabling said hydraulic means to cushion said forces, and resilient cushion means connected to said member for cushioning said below level forces thereon.

2. In a railway c-ar having a fixed .center sill, a cushion underframe comprising a sill member movable longitudinally in said ffixed sill, a yoke -slidable longitudinally in said sill member and connected to a coupler projecting forwardly therefrom, resilient cushioning means in said sill member for resisting longitudinal movement of said yoke relative thereto, a hydraulic cushioning unit in said fixed sill .rearwardly of said sill member, said hydraulic unit including7 a viscous liquid-filled cylinder fixed to and extendingy longitudinally of said fixed sill and a piston having `a head slidable longitudinally in said cylinder and a stem project-ing forwardly Itherefrom and secured for longitudinal movement in unison to a rear wall of said member, orifice means in said head for restricted ow therethrough of said fluid on sliding of said piston relative to said cylinder, v-alve means lon said head for normally .blocking ow of said liquid in one direction through said orifice means and lthereby locking said piston and sill member against longitudinal movement in the opposite direction, and control means actuated `by said yoke on rearward movement thereof relative to said sill member under bufiing forces on said coupler at and above a predetermined level for unseat-ing said valve means yand enabling said hydraulic means to cushion said bufling forces, said resilient cushioning means cushioning bufiing and draft forces between said sill member and `coupler below said level.

3. In a railway car having a fixed center sill, a cushion underframe comprising a sill member movable longitudinally in said fixed sill, a yoke slidable longitudinally in said sill member `and connected to Ia coupler projecting forwardly therefrom, resilient cushioning means in said sill member `for cushioning buf-ling and draft forces between said member and yoke on relative longitudinal movement thereof, a hydraulic cushioning unit in said Ifixed `sill rearwardly yof said sill member, said hydraulic unit including a viscous liquid-filled cyl-inder fixed to and extending longitudinally of said fixed sill and a piston having ahead slidable longitudinally in said cylinder and a stem projecting forwardly therefrom and secu-red for longitudinal movement in unison to a rear wall of said member, orifice means in said head for restricted iiow therethrough of said fin-id on sliding of said piston rel-ative to said cylinder, valve -means on said 'head and normally blocking fiow of said liquid forwardly through said orifice means for locking said piston and sill member against rearward movement .relative to said fixed sill, a control rod operatively connected to sa-id valve means, said control rod being actuatable by said yoke on rearward movement thereof in response to buffing forces thereon at and above a predetermined level for unseating said valve means and releasing said sill member for rearward movement under cushioning by said hydraulic cushioning means, land spring means -for returning said sill member to normal position under dampening by said hydraulic cushioning means..

4. In a railway car having a fixed center sill, a cushion underframe comprising a sill member movable longitudinally in said fixed sill, a yoke slidable longitudinally in said sill member and connected to a coupler projected forwardly thereof, resilient cushioning means in said sill member for cushioning bufiing and draft forces between said member and yoke on relative longitudinal movement thereof, a hydraulic cushioning unit in said fixed sill rearwardly of said sill member, said hydraulic unit including a viscous liquid-filled cylinder fixed to and extending longitudinally of said fixed sill and a piston having a head slidable longitudinally in said cylinder and a stem projecting forwardly therefrom and secured for longitudinal movement in unison to a rear wall of said member, orifice means in said head for restricted ow therethrough of said fluid on sliding of said piston relative to said cylinder, valve means on said head and normally blocking flow of said liquid forwardly through said orifice means for locking said piston and sill member against rearward movement relative to said fixed sill, a control rod operatively connected to said valve means and axially shiftable in and extending through said piston and into a yoke-receiving pocket in said sill member, said rod being normally spaced rearwardly from` said yoke and engageable and actuatable thereby on rearward move# ment thereof in response to bufling forces thereon at and above a predetermined level for unseating said valve means and releasing said sill member for forward movement under cushioning by said hydraulic cushioning means, and spring means for returning said sill member to normal position under dampening by said hydraulic cushioning means.

5. In a railway car having a fixed center sill, a cushion underframe comprising a oating sill member movable longitudinally in said fixed sill, hydraulic cushioning means in said fixed sill and connected for compression by said sill member on said longitudinal movement thereof, said hydraulic means including a cylinder filled with a viscous liquid and a piston having a head slidable in said cylinder, a plurality of orifice means in said head for passage of said liquid therethrough, check valve means permitting said liquid to iiow in one direction through one of said orifice means for enabling said hydraulic means to expand, check valve means preventing compression of said hydraulic means by blocking flow of said liquid in the opposite direction through said other orifice means except under bufling forces on said sill member at and above a predetermined level, and resilient cushioning means connected to said sill member for cushioning buffing and draft forces thereon below said level.

6. A cushion underframe for a railway car having a fixed center sill and a coupler, comprising a sill member movable longitudinally in said fixed sill and mounting said coupler, resilient cushioning means acting between said sill member and coupler for cushioning longitudinal forces on said coupler below a predetermined level, and hydraulic cushioning means in said fixed sill rearwardly of said sill member for cushioning bufiing forces on said coupler at and above said level, said hydraulic means including a housing stationarily mounted in said fixed sill, a piston slidable in said housing and connected to said sill member for movement therewith longitudinally of said fixed sill, and valve means for blocking rearward movement of said piston and sill member except under said at and above level buffing forces.

7. A cushion underfrarne for a railway car having a fixed center sill and a coupler, comprising a sill member slidable longitudinally in said fixed sill, a yoke in said sill member and connected to said coupler, resilient cushioning means in said yoke and acting between said coupler and sill member for cushioning longitudinal forces on said coupler below a predetermined level, and hydraulic cushioning means in said fixed sill rearwardly of said sill member for cushioning buffing forces on said coupler at and above said level, said hydraulic means including a housing stationarily mounted in said fixed sill, a piston slidable in said housing and connected to said sill member for movement therewith longitudinally of said fixed sill, and valve means for blocking rearward movement of said piston and sill member except under said at and above level buing forces.

8. A cushion underframe for a railway car having a fixed center sill and coupler, comprising a sill member slidable longitudinally in said fixed sill, a yoke in said sill member and connected to said coupler, resilient cushioning means in said yoke and acting between said couplet and sill member for cushioning longitudinal forces on said coupler below a predetermined level, hydraulic cushioning means in said fixed sill rearwardly of said sill member for cushioning buing forces on said coupler at and above said level, said hydraulic means including a housing stationarily mounted in said xed sill, a piston slidable in said housing and connected to said sill member for movement therewith longitudinally of said xed sill, and Valve means for blocking rearward movement of said piston and sill member except under said at and above level bufng forces, and spring means acting between said sill member and Xed sill for returning said sill member and piston to neutral position.

9. A cushion underframe for a railway car having a -Xed center sill and a coupler, comprising a sill member movable longitudinally in said xed sill and mounting said coupler, resilient cushioning means in said sill member and acting therebetween and said coupler for cushioning longitudinal forces on said coupler below a predetermined level, hydraulic lcushioning means mounted in said xed sill rearwardly of said sill member for cushioning buing forces on said coupler at and above said level, said hydraulic means including a housing stationarily mounted in said iXed sill, a piston slidable in said housing and connected to said sill member for movement therewith longitudinally of said Xed sill, check valve means for blocking rearward movement of said piston and sill member except under said at and above level bufting forces, and other check valve means controlling forward movement of said piston in said housing for enabling said hydraulic means to dampen draft forces applied when said piston is in a rearward position, and spring means acting between said sill member and xed sill and cooperating with said other check Valve means for returning said sill member and piston to neutral position.

References Cited by the Examiner UNITED STATES PATENTS 1,036,340 8/1912 Rockwell et al 267-65 1,434,024 10/ 1922 Ree 188-96 2,064,891 12/ 1936 Egen 213--8 3,150,781 9/1964 HOuSman et al 213-23 3,173,552 3/1965 ZanoW Z13-F43 ARTHUR L. LA POINT, Primary Examiner.

B. FAUST, Assistant Examiner. 

4. IN A RAILWAY CAR HAVING A FIXED CENTER SILL, A CUSHION UNDERFRAME COMPRISING A SILL MEMBER MOVABLE LONGITUDINALLY IN SAID FIXED SILL, A YOKE SLIDABLE LONGITUDINALLY IN SAID SILL MEMBER AND CONNECTED TO A COUPLER PROJECTED FORWARDLY THEREOF, RESILIENT CUSHIONING MEANS IN SAID SILL MEMBER FOR CUSHIONING BUFFING AND DRAFT FORCES BETWEEN SAID MEMBER AND YOKE ON RELATIVE LONGITUDINAL MOVEMENT THEREOF, A HYDRAULIC CUSHIONING UNIT IN SAID FIXED SILL REARWARDLY OF SAID SILL MEMBER, SAID HYDRAULIC UNIT INCLUDING A VISCOUS LIQUID-FILLED CYLINDER FIXED TO AND EXTENDING LONGITUDINALLY OF SAID FIXED SILL AND A PISTON HAVING A HEAD SLIDABLE LONGITUDINALLY IN SAID CYLINDER AND A STEM PROJECTING FORWARDLY THEREFROM AND SECURED FOR LONGITUDINAL MOVEMENT IN UNISON TO A REAR WALL OF SAID MEMBER, ORIFICE MEANS IN SAID HEAD FOR RESTRICTED FLOW THERETHROUGH OF SAID FLUID ON SLIDING OF SAID PISTON RELATIVE TO SAID CYLINDER, VALVE MEANS ON SAID HEAD AND NORMALLY BLOCKING FLOW OF SAID LIQUID FORWARDLY THROUGH SAID ORIFICE MEANS FOR LOCKING SAID PISTON AND SILL MEMBER AGAINST REARWARD MOVEMENT RELATIVE TO SAID FIXED SILL, A CONTROL ROD OPERATIVELY CONNECTED TO SAID VALVE MEANS AND AXIALLY SHIFTABLE IN AND EXTENDING THROUGH SAID PISTON AND INTO A YOKE-RECEIVING POCKET IN SAID SILL MEMBER, SAID ROD BEING NORMALLY SPACED REARWARDLY FROM SAID YOKE AND ENGAGEABLE AND ACTUATABLE THEREBY ON REARWARD MOVEMENT THEREOF IN RESPONSE TO BUFFING FORCES THEREON AT AND ABOVE A PREDETERMINED LEVEL FOR UNSEATING SAID VALVE MEANS AND RELEASING SAID SILL MEMBER FOR FORWARD MOVEMENT UNDER CUSHIONING BY SAID HYDRAULIC CUSHIONING MEANS, AND SPRING MEANS FOR RETURNING SAID SILL MEMBER TO NORMAL POSITION UNDER DAMPENING BY SAID HYDRAULIC CUSHIONING MEANS. 